Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Trabecular Meshwork”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,171 records · Page 65Linked to original sources
PubMed1986

Elimination of sodium hyaluronate-induced decrease in outflow facility with hyaluronidase.

The use of intraocular sodium hyaluronate is complicated by a postoperative rise in intraocular pressure (IOP). The rise in IOP is thought to stem from a "clogging" at the trabecular meshwork by the large molecules of hyaluronate. This study uses serial tonographic measurements in an animal model to document this change in outflow facility. Furthermore, we investigate the ability of the enzyme hyaluronidase to cleave the hyaluronate into smaller molecular weight fragments, in vivo, and thereby eliminate the change in outflow facility. This report demonstrates the potential usefulness of this enzyme and documents the lack of harmful side effects histopathologically.

Animals↗
PubMed1996

Experimental microendoscopic photoablative laser goniotomy as a surgical model for the treatment of dysgenetic glaucoma.

PURPOSE: The aim of this study was to investigate the feasibility of photoablative Er:YAG laser goniotomy under microendoscopic control in a surgical cloudy corneal model of primary infantile glaucoma. METHODS: Pectinate ligaments of 12 freshly enucleated cadaver porcine eyes were treated by ab interno single-pulse (5 mJ, 200 microseconds) Er:YAG laser (2.94 microns) photoablation. Through a clear corneal incision near the limbus an ophthalmic microendoscope (18 and 20 gauge) was inserted into the anterior chamber. Internal structures were observed and photoablative laser goniotomy was conducted under video guidance. Following treatment all eyes were prepared for light and scanning electron microscopy. RESULTS: Anterior chamber angle structures and tissue photoablation were clearly visualized on the videoscreen using ophthalmic microendoscopy. Energy settings of 5 mJ per pulse proved to be sufficient for reproducible photoablation of pectinate ligaments, accompanied by the root of the iris falling back and exposing trabecular meshwork. This was confirmed histopathologically. Scatter thermal damage was less than 30 microns. CONCLUSION: This new therapeutic modality, which combines endoscopic visualization of the internal structures with photoablative laser goniotomy, can be effective in the management of dysgenetic glaucoma in the presence of a cloudy cornea. High reproducibility of contact laser photoablation enabled sufficient control of incision depth and was not accompanied by inadvertent tissue damage to adjacent intraocular structures.

Animals↗
PubMed1983

Laser trabeculoplasty in open angle glaucoma.

We have treated 54 eyes that were considered candidates for trabeculectomy with argon laser trabeculoplasty. One hundred burns were placed in the trabecular meshwork right in front of the scleral spur in the lower two quadrants. Average prelaser IOP was 26.2 mmHg and average postlaser IOP was 18.3 mmHg. Four eyes (7.4%) went to further surgery. Mean follow-up time was 3.5 months. There were few complications. Most important was a transitory increase of IOP larger than 10 mmHg in 7 eyes (13.0%). There was one case of acute iridocyclitis.

Adult↗
PubMed2005

Oxygenation by COX-2 (cyclo-oxygenase-2) of 3-HETE (3-hydroxyeicosatetraenoic acid), a fungal mimetic of arachidonic acid, produces a cascade of novel bioactive 3-hydroxyeicosanoids.

Cyclo-oxygenases-1/2 (COX-1/2) catalyse the oxygenation of AA (arachidonic acid) and related polyunsaturated fatty acids to endoperoxide precursors of prostanoids. COX-1 is referred to as a constitutive enzyme involved in haemostasis, whereas COX-2 is an inducible enzyme expressed in inflammatory diseases and cancer. The fungus Dipodascopsis uninucleata has been shown by us to convert exogenous AA into 3(R)-HETE [3(R)-hydroxy-5Z,8Z,11Z,14Z-eicosatetraenoic acid]. 3R-HETE is stereochemically identical with AA, except that a hydroxy group is attached at its C-3 position. Molecular modelling studies with 3-HETE and COX-1/2 revealed a similar enzyme-substrate structure as reported for AA and COX-1/2. Here, we report that 3-HETE is an appropriate substrate for COX-1 and -2, albeit with a lower activity of oxygenation than AA. Oxygenation of 3-HETE by COX-2 produced a novel cascade of 3-hydroxyeicosanoids, as identified with EI (electron impact)-GC-MS, LC-MS-ES (electrospray) and LC-MS-API (atmospheric pressure ionization) methods. Evidence for in vitro production of 3-hydroxy-PGE2 (3-hydroxy-prostaglandin E2) was obtained upon infection of HeLa cells with Candida albicans at an MOI (multiplicity of infection) of 100. Analogous to interaction of AA and aspirin-treated COX-2, 3-HETE was transformed by acetylated COX-2 to 3,15-di-HETE (3,15-dihydroxy-HETE), whereby C-15 showed the (R)-stereochemistry. 3-Hydroxy-PGs are potent biologically active compounds. Thus 3-hydroxy-PGE2 induced interleukin-6 gene expression via the EP3 receptor (PGE2 receptor 3) in A549 cells, and raised cAMP levels via the EP4 receptor in Jurkat cells. Moreover, 3R,15S-di-HETE triggered the opening of the K+ channel in HTM (human trabecular meshwork) cells, as measured by the patch-clamp technique. Since many fatty acid disorders are associated with an 'escape' of 3-hydroxy fatty acids from the b-oxidation cycle, the production of 3-hydroxyeicosanoids may be critical in modulation of effects of endogenously produced eicosanoids.

Adenocarcinoma↗
PubMed2002

Adult-onset primary open-angle glaucoma caused by mutations in optineurin.

Primary open-angle glaucoma (POAG) affects 33 million individuals worldwide and is a leading cause of blindness. In a study of 54 families with autosomal dominantly inherited adult-onset POAG, we identified the causative gene on chromosome 10p14 and designated it OPTN (for "optineurin"). Sequence alterations in OPTN were found in 16.7% of families with hereditary POAG, including individuals with normal intraocular pressure. The OPTN gene codes for a conserved 66-kilodalton protein of unknown function that has been implicated in the tumor necrosis factor-alpha signaling pathway and that interacts with diverse proteins including Huntingtin, Ras-associated protein RAB8, and transcription factor IIIA. Optineurin is expressed in trabecular meshwork, nonpigmented ciliary epithelium, retina, and brain, and we speculate that it plays a neuroprotective role.

Adult↗
PubMed1999

Identification and isolation of differentially expressed genes from very small tissue samples.

Identification of differentially expressed genes from tissue samples weighing only a few milligrams has remained a major challenge. Here, we describe a novel and simple strategy that uses standard molecular biology equipment and commercially available kits. The approach combines isolation of total RNA by silica-gel binding, reverse transcription using anchored modified, 5' end enhancers oligonucleotides, exponential amplification of the single-stranded cDNA and hybridization to high-density cDNA filter arrays. The method was tested by comparing genes expressed on freshly isolated human trabecular meshwork tissue with those expressed in corresponding primary cells at third passage. Validation was achieved by using two biological properties: (i) hybridization, to identify the differentially expressed genes, and (ii) PCR amplification, to confirm their distinct expression. The strategy presented allows the identification of differentially expressed genes and/or uncharacterized expressed sequence tags (ESTs) in very small tissue samples, including those from clinical specimens.

Biotechnology↗
PubMed1996

Olopatadine (AL-4943A): ligand binding and functional studies on a novel, long acting H1-selective histamine antagonist and anti-allergic agent for use in allergic conjunctivitis.

AL-4943A (Olopatadine) is a new antihistaminic and anti-allergic drug. It was tested for its ability to compete for [3H]pyrilamine, [3H]tiotidine and [3H]N-methyl histamine binding to H1, H2 and H3 histamine receptors, respectively. AL-4943A exhibited the highest affinity (Ki = 41.1 +/- 6.0 nM) for H1-receptors and a significantly lower affinity for H2- (Ki = 43,437 +/- 6,257 nM) and H3-receptors (Ki = 171,666 +/- 6,774 nM), respectively. These data showed AL-4943A to be an H1-selective compound, being 1,059- and 4,177-times more selective for H1- than H2- and H3-receptors. AL-4943A was more H1-selective than levocabastine, ketotifen, antazoline and pheniramine and, also, exhibited a low affinity for 38 nonhistamine receptor binding sites. AL-4943A antagonized histamine-induced phosphoinositide (PI) turnover in cultured human conjunctival epithelial cells (IC50 = 9.5 +/- 1.5 nM, n = 3), human corneal fibroblasts (IC50 = 19 nM) and transformed human trabecular meshwork cells (IC50 = 39.9 nM). These data have shown AL-4943A to be a high affinity, high potency H1-selective histamine antagonist. This information, coupled with a long duration of action in an in vivo model of allergic conjunctivitis, suggests that AL-4943A may be a useful drug to treat various ocular allergic diseases, including allergic conjunctivitis.

Anti-Allergic Agents↗
PubMed1978

Inflammatory response of guinea pig to injected limbal tissue.

This study examined the possibility that homologous limbal tissue, including trabecular meshwork, serving as an antigen, could elicit inflammatory cells responsible for both aqueous obstruction and inflammation; the possible role of this response in ocular disease was also studied. Four sets of guinea pigs were sensitized with complete Freund's adjuvant. One set received just adjuvant and saline, one set received adjuvant plus uvea, and two sets received adjuvant plus limbal tissue. The animal injected with only adjuvant and saline all showed normal ocular histology. Sensitizing guinea pigs with limbus and adjuvant produced mononuclear infiltration of the uvea, trabeculum, and episclera. Lymphocytes and plasma cells predominated. The response induced by the limbus seemed to consist of two components: a uveal and a specific limbal component. The lymphoid infiltration of the uvea was identical to the response induced by uveal antigen in our uvea control group. The limbal component was characterized by clusters of lymphocytes and plasma cells in the trabecular and episcleral regions. This study showed that limbal tissue antigen induces an inflammatory response in both uvea and limbus, and that the inflammatory response in the trabeculum is greater with limbal than uveal antigen.

Animals↗
PubMed1983

Surgical management of chronic glaucoma in aphakia.

The surgical management of glaucoma in aphakia has been limited by poor success in the control of intraocular pressure and serious postoperative complications that threaten vision. A consecutive series of trabeculectomy filtering procedures in aphakic eyes with a mean preoperative intraocular pressure of 38 mmHg was followed for an average of 26 months and revealed a 62% control of intraocular pressure at 21 mmHg or less. Five additional patients (24%) had pressures lower than 21 mmHg following digital massage. The complication of decreased visual acuity following surgery was significant but not directly related to the surgical procedure. Another patient population with glaucoma and aphakia with a mean preoperative pressure of 25 mmHg was treated with laser trabeculoplasty. In 12 of 15 patients (80%) intraocular pressure was lower than 22 mmHg for an average of eight months and did not require glaucoma surgery. There were no significant complications following this therapy and all patients retained preoperative level of visual acuity. In aphakic patients who have uncontrolled glaucoma on maximal medical therapy, surgery is indicated. We recommend the following approach to surgical management: (1) Laser treatment to the trabecular meshwork if the angle is open; (2) if this fails, or the angle is extensively closed, a trabeculectomy filtering procedure is suggested; (3) cyclocryotherapy has been effective in controlling pressure but the unpredictable loss of vision has prompted caution in seeing eyes; (4) cyclodialysis; and (5) transpupillary or transscleral treatment of the ciliary processes are additional modes of therapy. Improved results of surgical treatment for glaucoma and aphakia have been encouraging and should be used when maximal medical therapy is ineffective.

Adult↗
PubMed1994

[Lectin electron microscopic histochemistry of exfoliative material from capsular glaucoma].

Exfoliative material of capsular glaucoma was studied by electron microscopic lectin histochemistry using sixteen kinds of lectin; PNA, RCA60 and 120, ABA, DBA, SBA, ConA, LCA, WGA, DSA, PHA-E4 and L4, UEA-I, Lotus, MAM, and SSA. The results indicated that sugar residues in exfoliative material on the lens and trabecular meshwork have the same characteristics, i.e., they contain glycoconjugates with sugar residues of beta-galactosyl, alpha-mannosyl, N-acetyl-D-glucosaminyl, and terminal sialic acid. The lectin staining pattern of microfibrils in exfoliative material, radially oriented fibrils and linear densities in the lens capsule, and zonular lamella was also similar to that of exfoliative material, and suggested their close association with exfoliative material. These results also indicated that lectin can be employed in the detection and identification of exfoliative material in various tissues.

Aged↗
PubMed1985

Fibronectin in human trabecular drainage channels.

Fibronectin, an extracellular glycoprotein, has been shown to be produced by human trabecular cells in culture by our group as well as Polansky and co-investigators. Studies of Rodrigues et al suggested that fibronectin may be one of several glycoproteins found in increased amounts in the corneoscleral trabecular meshwork of glaucomatous eyes. The authors have developed a sensitive immunoassay utilizing avidin-biotinylated enzyme complex (ABC) to detect low levels of fibronectin in frozen sections of human eyes. The authors have used this immunoassay together with a perfusion technique to demonstrate distribution patterns of fibronectin present in human aqueous drainage channels. The authors found that fibronectin is present in larger quantities in the aqueous drainage channels than in the surrounding tissues in 18 eyes from older patients.

Aged↗
PubMed1986

Factors affecting the results of argon laser trabeculoplasty in open-angle glaucoma.

Argon laser trabeculoplasty (ALT) was performed in 232 eyes of 180 patients affected by uncontrolled primary open-angle glaucoma (POAG), exfoliation syndrome glaucoma (ESG) or pigment dispersion syndrome glaucoma (PDSG). Mean follow-up was 9 months (3-22). Mean IOP change was -21.6% (+/- 19) from the initial value. The effect of IOP was larger in patients with ESG, PDSG, and in POAG cases with more pigmented trabecular meshwork. No relationship was found between IOP changes and age or refraction of patients; the association with iridoplasty did not influence final results. An Octopus computerized perimeter was used for pre and post-treatment visual field tests. In 113 eyes Octopus exams met the requirements for quantitative analysis. In this group 17% of visual field improved, 64% remained stable and 19% worsened. A good functional response was more frequent among the eyes with less advanced disease.

Aged↗
PubMed1986

[Experiences with laser therapy in different forms of glaucoma with open and closed chamber angle].

Results of laser treatment of open-angle and angle-closure glaucomas are communicated. Argon laser trabeculoplasty was performed in 78 eyes with open-angle glaucoma. The most favorable site for photocoagulation was the gone between the pigmented and nonpigmented trabecular meshwork. Forty-two eyes with angle-closure glaucoma were treated by argon laser gonioplasty. This method proved successful in chronic angle-closure glaucoma and for the prophylactic management of acute angle-closure glaucomas. A combination of argon laser gonioplasty and argon laser trabeculoplasty was used in 16 eyes. Both methods were found to be effective in treating certain forms of juvenile glaucoma. A further 11 eyes with acute angle-closure glaucoma were treated by Nd-YAG laser iridotomy, 9 of them successfully.

Anterior Chamber↗
PubMed2004

Expression analysis of the matrix GLA protein and VE-cadherin gene promoters in the outflow pathway.

PURPOSE: To test the ability of promoter fragments from the matrix Gla protein (MGP) and vascular endothelial-cadherin (VE-cad) genes to target gene expression in a specific manner in the cells of the outflow pathway, by using adenoviral-mediated gene transfer in organ culture. METHODS: Perfused anterior segments of human eyes were infected with replication-deficient recombinant adenoviruses expressing the beta-galactosidase reporter gene driven by the cytomegalovirus (CMV; control, n = 6), MGP (n = 6), or VE-cad (n = 12) promoters. Forty-eight hours after infection, the anterior segments were fixed and stained for beta-galactosidase activity. The distribution of beta-galactosidase expression was analyzed in paraffin-embedded sections. RESULTS: The MGP promoter fragment resulted in beta-galactosidase expression by the cells of the conventional outflow pathway and did not show any activity in the corneal endothelium or other cells posterior to the scleral spur. Adenovirus containing the VE-cad promoter fragment showed functionality of the promoter in vascular endothelial cells, but failed to produce any detectable expression in the cells of the outflow pathway. CONCLUSIONS: Directed expression by the MGP gene promoter specifically to the trabecular meshwork (TM) provides a new tool for specific gene transfer to the outflow pathway. Results with the VE-cad promoter fragment indicate possible differences in the regulation of this gene between vascular and Schlemm's canal endothelial cells. Taken together, these data demonstrate the feasibility of targeted gene expression to the outflow pathway cells using tissue specific promoters.

Adenoviruses, Human↗
PubMed1979

Morphological studies about the efficiency of laser beams upon the structures of the angle of the anterior chamber. Facts and concepts related to the treatment of the chronic simple glaucoma.

Working at a power density above optical breakdown threshold, irradiation effects upon the angle of the anterior chamber of the Macaca speciosa monkey by a Nd glass Q-switched laser, have been analysed with scanning electron microscopy. Two different damage effects can be identified: openings of Schlemm's canal and the creation of a cyclodialysis, that is opening the uveoscleral outflow routes; the latter may be a more effective one than the former. Also a third mechanism, namely a structural alteration of the trabecular meshwork, at the molecular level by laser action, has been inferred. The physical effects leading to optically induced mechanical damage are discussed. Applicability of such effects upon the morphological findings described here, is limited and to a greater part speculative. A better definition of the physical parameters, required for optimal therapeutical damage effects in the treatment of the wide angle glaucoma may be obtained by trial and error methods, which are guided by the results of electron microscopical analyses of samples obtained from in vivo and in vitro experiments.

Animals↗
PubMed1977

[Trabeculectomy: surgical technique, results, indications (author's transl)].

In this teaching-course special emphasis is given on surgical techniques and postoperative care of trabeculectomy. The follow-up of 114 eyes of 103 patients is reported. High tension in the early postoperative phase allowed no prediction of the later results. After 3 months 11%, and after one year 39% of the operated eyes with simple glaucoma had a tension higher than 22 mm Hg, even if drugs were given. Different sites of the excision in regard to the trabecular meshwork and Schlemm's canal gave no statistically different results. The filtering blebs have the tendency to develop in two directions, either scarring or becoming cystic. The cystic filtering blebs give better functional results. The development of the filtering bleb was inversely proportional to the height of the tension but went parallel to the facility of outflow. The visual acuity diminished in 35%, mostly due to cataract-formation and improved in 3%. Different complications happened in 6%. The authors consider the trabeculectomy to be the operation of choice for almost all forms of glaucoma.

Follow-Up Studies↗
PubMed1983

Adenoma of the iris-pigment epithelium.

An 11-year-old boy was noted to have a multinodular tumor involving the peripheral iris and trabecular meshwork in his left eye. During the next 12 years, the lesion slowly enlarged and produced pigmentary dispersion in the anterior chamber and glaucomatous changes in the optic disc. Histopathologic examination of the tumor after its removal by iridocyclectomy revealed features consistent with the diagnosis of adenoma of the iris-pigment epithelium. A correlation between the clinical and histopathologic features is presented. Clinical features that can be helpful in differentiating an adenoma of the iris-pigment epithelium from a malignant melanoma are discussed.

Adenoma↗
PubMed1997

Expanding forces in aqueous outflow pathways of a nonaccommodating mammal: an approach via comparative dynamic morphology.

Six dog eyes were fixed by intracameral perfusion of fixative at pressures of 0, 5, 10, 15, 20, and 25 cm of water. Eight dog eyes were fixed after the injection in both ocular chambers of a number of cholinergic agents, either singly or in combination. Under the effect of miotics and under increased ocular pressure, the aqueous pathways expand. An analysis of the forces involved in expansion of the exit pathways reveals the primary role of the detached ciliary body in nonaccommodating mammals. Two mechanisms appear to have been conserved in dogs and humans throughout evolution. The first is an active mechanism: the opening of the trabecular meshwork as a consequence of the combined action of the ciliary muscle and the iris and its insertion ligaments-the uveoscleral trabeculate-in dogs, and the longitudinal portion of the ciliary muscle and scleral spur in humans. The second is a passive mechanism: the infundibular arrangement of the drainage structures assisted by the traction on the zonular ligament of the lens, which responds to an increase in pressure in the anterior chamber by widening the pathways, thus favoring outflow.

Accommodation, Ocular↗